Mobile communication devices such as cellular phones or smart phones send and receive data through wireless communications channels. Mobile communication devices and the base stations of a cellular network may communicate data using a temporary block flow (TBF) connection. A TBF is a physical connection used by two radio resource entities, such as a mobile communication device and a base station, to support the unidirectional transfer of protocol data units on packet data physical channels. A TBF is temporary and maintained only for the duration of the data transfer, which is until there are no more data blocks to be transmitted. Once all data blocks buffered for transfer are sent to the mobile communication device, the TBF is released at both ends of the communications channel. Each TBF is assigned a temporary flow identifier (TFI) that uniquely identifies the TBF and the sender on a packet data physical channel.
The data transmitted over a TBF is arranged into a number of data blocks, with each block assigned a unique block sequence number (BSN). The BSN determines the order in which the data blocks should be transmitted such that blocks with sequential BSNs are transmitted sequentially. The mobile communication device has a receive window, which is a moving range of BSNs for data blocks that the mobile communication device expects from the network. For example, at the beginning of a TBF, the receive window may include BSNs 0 through 1024. After the mobile communication device receives data blocks numbered 0 through 9, the receive window may slide over to BSN range 10-1034. The network may also send control messages to prepare the mobile communication device for a change in the TBF or to end the current TBF and start a new TBF. One such control message is a TBF release message along with a new downlink assignment message, which ends the current TBF and initiates another TBF using the same TFI. Another control message is a timeslot reconfigure message that assigns a new TFI to the current TBF.
Data reception on a mobile communication device may be subject to errors caused by interference with the wireless signal. For example, there may be ambient radio interference or physical objects that impede transmission of the TBF from a base station to a mobile communication device. The mobile communication device may also have more than one radio frequency (RF) resource, such as a multi-subscriber identity module (multi-SIM) multi-active (MSMA) communication device, in which case transmission by one RF resource may interfere with the reception of the other RF resource. Thus, mobile communication devices may not receive one or more data blocks or control messages sent by a network. This is especially problematic if the mobile communication device misses control messages indicating an end or change to a TBF. For example, a mobile communication device may not receive a TBF release and new downlink assignment. When this occurs, the mobile communication device continues to operate as if the current TBF has not ended and waits for a data block with a BSN that is within the expected receive window. The mobile communication device ignores any received data blocks that are not within the expected receive window (“out-of-window data blocks”). Thus, the mobile communication device will ignore any data blocks sent through a new TBF, which would start with a BSN of zero. This situation causes a stall in the mobile communication device, which may last for a long time before the stall is corrected. A stall may also occur if the mobile communication device misses a timeslot reconfigure message because the mobile communication device does not switch to the new TFI. The data blocks sent by the network using the old TFI are intended for another device, so the mobile communication device again receives out-of-window data blocks. Thus, a stall may persist for an extended period.